Attachment for range-finders.



No. 840,778. PATENTED JAN. 8,;907. K. 0. LBQN." ATTACHMENT POR RANGEPINDERS.

APPLICATION FILED MAY25,1905. f

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N0. 840,778. Y PATENTED JAN. 8, 1907.

K. 0. LEON.

ATTACHMENT TOR RANGE TINDBRS.

APPLICATION FILED MAY 25, 1905.

4 SHEETS-SHEET 2.

Nun 62? uIll! No. 840,778. PATENTED JAN. 8, 1907. K. 0. LEON. ATTACHMENTFOR RANGE FINDERS.

APPLICATION FILED MAY25,1905.

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n 67; f. EN l a Wit nasse/' 59 69 77 Inventar No. 840,778. PATENTED JAN.8, 1907. K. 0. LEON.

ATTACHMENT POR RANGE FINDBRS.

4 SHEETS-SHEBT 4.

UNITED STATES PATENT OFFTCE.

Specicaton of ALetters Patent.

Patented Jan. 8, 1907.

Application filed May 25, 1905. Serial No. 262,296.

To all whom it may concern,.- Be it known that I, KARL OsKAR LEON, asubject of the King of Sweden, and a resident of Riddargatan 38,Stockholm, in the Kingdom of Sweden, have invented certain -new anduseful Improvements in Attachments for Range-Finders, of which thefollowing is a speciication, reference being had therein to theaccompanying drawings.

It is old to cause a pointer or the like arranged to turn. about a pointa map or chart to automatically move according to the axis of a sightingapparatus, such as a telescope, when the latter is placed at a spot onthe ground corresponding to the location of the pivot of the ruler onthe map or chart. The indication on the map or chart of the position ofthe object observed has hitherto been performed either by the use of tworulers or pointers turning abou/t different points,'in which caseobviously two points of observation are necessary, orit has been tried.to indicate the distance of the object from the point of observation bymeans of a galvanometer situated at the other spot. In battering movableobj ects by secondary bombardment none of Vthese methods fulfils theconditions required as to accuracy and despatch in indicating theinstantaneous position of the movable object to be battered, so much theless as most of the apparatus hitherto devised do not work automaticallat all in that the ruler does not automatica ly follow the movements ofthe sighting apparatus during its turning; but the true direction of theruler is. to be` found by turning it to and back until a galvanometerplaced in a Wheatstones bridge takes up a determinate posi.

tion.

When two points of observation are used for indicating the instantaneousposition of the object to be battered, the location of an object can bedetermined only within a limited space, since in the contrary case theangle between the two sighting-lines will be too obtuse or too acute toallow of a sufficiently distinct determination, and, further, theprocedure will be much more complicated than in the case of only onepoint of observation being used, due to thefact that the system isduplicated and requires more adjust-y ments to b e made, whereby specialsystems of apparatus, such as telephone or telegraph.

lines between the points of observation, are necessary to enable theobservers to communicate, it being obviously necessary that the Aanismof the indicator.

observers sight at the same object, which in the presence of severalhostile ships cannot be attained without certain arrangements..

As before stated, a s principle' of only one point of observation isold; but` that system did not work automatically, and the distanceg'ofthe object from the point of observation was indicated at the other spotby means of 'a galvanometer placed at the latter spot, vby which theindications` obtained were not sufliciently accurate on 'account of theresistances of the long lines of connection.

The present invention provides an arran ethe invention consists in thecombination,

with the known movablepointer, of a cursor that is caused toautomatically move along the pointer b means of electrical impulsesarising when t e sighting apparatus is turned in the vertical plane, sothat the position of the cursor always corresponds to that of thelobject observed. Thev distance and the direction of the object from thesecond spot aredirectly indicated by a `pointer journaled to move abouta point corresponding to the re.-

, ceiving-station, the cursor engagingaI longitudinal groove in the saidpointer. f

The accompanying drawings illustrate, by way of example, a system of'contrivances ystem based on the constructed so as to make it possibleto 'read oi at the battery or place oi' firing the varying range andstation of an object-,for instance, a ship-kept in view at the place ofobservation. y

Figure 1 shows the observation contrivance or determinator in elevationand partial section. Fig. 2 is a detail showing in elevation one ofthemagnetic inductorsof the determinator, Fig. 1. Fig. 3 is a topv planviewof the indicator. Fig. 4 is a top plan View of the motivemechanismof the indicator, Fig. 3, which, as shown, is inclosed in a boxthe lid of which is removed in Fig.

4. Fig. 5 is a section in linel A A in Fig. 4, viewed from theright-hand side. Fig.'6 is a detail showing a part of the motive mech-Fig. '7 is a diagram showingthe circuit connections between thedeterminator andy "the indicator.

shows in elevation and partial section another form of construction ofthe determinator adapted to work with battery-current.

Fig. 9 1s a detail showing the contact ar- Fig. 8

'3, which itself rests on a fixed support 4.

The telesco ve is at its off end movab e about a horizonta shaft orhorizontal pivots 5, its fore end resting on a movable lever 6, suported by a spiral spring 7 or the like, t` e tension of which ismeasured in such a way that most of the weight of the telescope isdislodged from the cursorl 9, movable lalong the screw 8. The telescopeand the frame, as

shown in Fig. 1, are constructed in their chief parts on the rinciplesof the Madsen range-finder, which at a comparatively small expense mightbe adapted for the purpose. As shown in Fig. 1, there is on the l underside of the telescope a ruler 10, resting telescope is effected by on an,adjusting-screw 11, situated vin the slide or' cursor 9. The adjustmentof the adjusting the screw 11 along a scale 12. The telescope isdirected toward the 'object of observation by turning the screw 8 ineither direction so that the cursor 9 is forced to move along the screwguided by a ruler 13 or the like. The contact-point of the ruler 1()against the adjusting-screw 1,1 being situated when the telescope is proerly adjusted somewhat higher than the crum or center of motion of thetelescope, it is easily seen that by causing the cursor 9 to move towardor away from the said center the telescope can be'directed toward a lessor more distant object. If a certain point at the water-line of a shipor, generally speaking, an object moving on the surface of the water iskept in View by the telescope, the varying inclination or angle ofdepression of the telescope is evidently dependent upon for the distanceof the object.

his principle in measuring distances, as. ,above stated, 1s before knownand applied-- for instance, inthe Madsen range-finder and'it need,therefore, not be closer described- The screw 8 can be turned in eitherdirection v by means of a crank 14, on the shaft of which there is aworm 15, engaging a worm-wheel 16 on the motion-transmitting shaft 17,from which the motion is transmitted by means fof a bevel-gear 18 to theshaft 19, eX- tending' centrally through the vertical hollow pivot ofthe instrurnent, thence by means of a bevel-gearu20 to a shaft 2 1',parallel with the screw 8, and finally by means of a cylindrical gearing22 to screw 8, which, consequently, on turningthe crank 14 either walywill turn in a corresponding direction. he, transmission of motion fromcrank 14 to screw 8 can of course be effected by any other suitablegearing; but` inasmuch as the directing ing the operator.

. ing-wires,

movement of the telescope takes place within a comparatively small angleit would answer the urpose if to a great turning angle of the cran 14lcorresponds a comparatively small turning of the screw 8. For turninthe telescope in the horizontal lane a cran 23 may be arranged, on theshaft of which there is a cog-wheel 24, engaging a wheel 25, the shaftof which is arallel to the axis of the crank and provide with a worm 26,engaging a segment 27 on the hollow pivot 28 entering vertically fromframe 2 into the operationboX. The mechanism for transmitting motionfrom crank 23 to pivot 28 may of course be differently arranged and neednot be made as shown in the drawing. In order to diminish the friction,frame 2 can suitably be mounted on rollers 29 on the upper surface ofthe operation-box. The cranks 14 and 23 may. conveniently be placed onopposite sides of the operation-bpX-the one, for instance, on the rightside 'and the other on the left-but they may as well be placed on anyside of the boX--for instance, on the side fac- Fastened to eachcrankshaft is, further, a wheel 30 or 31, respectively engaging a 'wheel32 or 33, respectlvely situated on the shaft of an inductor or armature3 5 or 36, respectively placed between the poles of a number ofpermanent magnets 34.

Fig. 2 shows in elevation one of the inductors 35. Each end of'thewinding is supposed to be connected with one of two rings 37 and 38,placed on the'inductor-shaft, but insulated from the same. A brush 39 isplaced in contact with the ring 37. Placed around the other ring 38there is a socket or shell 40, havinga contact-arm 43, entering betweentwo contact pieces or springs 41 42', Fig. 7. When the inductor isrotated in one or the other direction, the shell 40 on the ring 38 turnswith the ring until contact 43 touches one or the other of thecontactsprings 41 and 42, which causes the shell 40 to stop, while thering 38 continues to rotate within it.- Thecontact-springs 41 and 42, aswell as the brush 39, lying against the ring 37, are connected by means.of conductors 44 45 46, respectively, each with one of three contacts47 48 49respectively, insulated'from the iron construction orconducting-body of the instrument. Fronf the contacts 47 48 49 threeinsulated conductors lead to the indicator at the place of iiring.Inductor 36, connected with crank 23, is provided with similarcontact'arrangements and conductso that lthe determinator is connectedwith the indicator by in all Asix conducting -.wires insulated from oneanother, said' wires being suitably inclosed within a single cable.

he indicator, as shown in Fig. 3, comrises a map 53 over the iield ofobservation.

his map comprises the observing-station as also the place of the batterywith regard to roo ISO

which the position of the object of observation-for instance, a ship-isto be indicated. The'iirst of these `two places coincides with the axisor fulcrum of a director or pointer 55, which moves in the horizontalplane and is rovided with a sighting-thread 54. When tliie instrumentworks, an angular motion is imparted to the pointer 54 in a manner to bedescribed, said motion corresponding with the horizontal motion of thetelescope. Movable along the pointer 55 is a .cursor 57, likewiseprovided with two sight- 1ng-threads 56, said cursor, when acted u on byelectrical means, acquiring a forwar or backward motion entirelyanalogous with the motion of `the cursor 9 of the determinator. Thesecond place coincides with the axis orfulcrum of a pointer 59, providedwith a scale 58, said pointer being likewisemovable in the horizontalplane, the motion of the point er 59 being effected by the combinedmotions of 'the pointer 55 and the cursor 57. The mechanism acting tomove the pointer 55 is inclosed in a box 60. (Shown in plan and with thelid removed in Fig. 4 and in section in Fig. 5.) The motionof thepointer is effected by means of two pairs of electromagnets, the onepair of which, comprising electromagnetsl61and 62, serves to turn thepointer in one direction, while the other pair, comprisingelectromagnets 63 and 64, serves to turn the pointer in the oppositedirection. For running the cursor 57 along the pointer 55 there are alsotwo electromagnet pairs, the one of which, comprising electromagnets 65and 66, serves to move the cursor in one direction, while the otherelectromagnet pair, comprising electromagnets 67 and 68, serves to movethe cursor in the opposite direction. The electromagnets mayconvenientlybe provided with adjustable pole-pieces 69. Placed betweenthe poles of each pair of electromagnets is a polarized armature, theone between the electromagnets 61 and`62 being marked by the figure 70,the one between the electromagnets 63 and 64 by 715the one betweenl theelectromagnets 65 and 66`by 72, and the one between the electromagnets67 and 68 by The circuit connections of the electromagnets 61 62 63 64serving to turnthe pointer 55 being exactly analogous to those of theelectromagnets 65 66 67 68, servlng for running the cursor 57 andl thearrangements for transmission of motion from the armatures 70 71 72 73,respectively, to the pointer 5 5 andcursor 57, respectively, being'likewise analogous, it will be sufficient to describe the circuits ofthe electromagnets 65. 66 67 68, serving to control the motion of thecursor 57 and the arrangements 'for theI transmission of motion from thearmatures 72 and 73 to the cursorv 57. The encabled conducting-wires 5051 52, connected with inductor 35, are led each to one of three contacts74 75 76 at the indicator. The electroinagnet pairs ,65 66 and 67 68 areconnected at one end withy one of the contacts 75 74, respectively, towhich the conductors from the contact-springs 42 41V'l at the inductor35 are led and at their other end with the third contact 76, connectedwith the brush 39.

' When the inductor 35 is turned in either direction, (by which contact43, as above stated, is brought in contact with one or the other of thecontact-springs 41 42,) an' alternating current will be transmitted frominductor 35 through one or the other or the two electromagnet pairs 6768 and 65 66. The circuits from inductor 36 through the electromagnetpairs 61 62 and- 63 64 are quite analogous. The electromagnet pairthrough which the inductor-current flows causes the polarized armatureto execute a number of oscillations corresponding to the angle ofrotation of the inductor, andl thus it is only needed to transmit, bymeans of some suitable mechanism, the oscillating motion of the armatureto pointer .55 or cursor 57, e respectively.

The armature 73 is shwn in Fig. 5 to be pivoted with its lower end at 77and provided at its upper part with two arms, forming together asemicircular arch. Each of the armsy carries a pin 80 81, respectively,or the like, working in a tangential direction on the teethl of a wheel82. This wheel 82 suitably constitutes the intermediate part of a seriesof wheels, the two outer parts'of which consist of a bevel-wheel 83 'anda ratchet-wheel 84, Fig. 6. The wheels 82 83 84 are firmly connected toone another or made in one piece and j ournaled on a shaft 85 in such amanner as to be able to rotate freely about the said shaft, the latterbeing carried at its ends in standards 86, mounted on the bottom of thebox 60. The armature 72, Fig. 4, of the-electromagnet pair 65 66 isconstructed in the same manner as the armature 73.0f the electromagnetpair 67 68 and, like the latter armature, acts .upon the teeth of awheel 87, Fig. 6, constituting the intermediate part of a series ofwheels of the same construction as that of the former series ofwheels-fi. e., consisting, except of the wheel 87, of a bevelwheel 88and a ratchet-wheel 89, both iirmly connected to the wheel 87 or made inone piece therewith and loosely mounted on shaft 85. On account of thetwo series of wheels facing each other the teeth of the. wheels 87 and89 will have a direction opposite to that of the teeth of the wheels 82and 84. Loosely mounted upon the middle portion of the shaft situatedbetween the two bevel-wheels 83 and 8 8 is a sleeve 90, havin 'at itsymiddle two diametricallyopposite ho es serving asbearings for the innerends of two pins 93, mounted at their outer ends in bearings 9'1 at oneside of a spur-wheel 92. Loosely mounted on each of the said pins is abevel-wheel 94 or 95, repectively, meshing with each of the two bevel-ISO " acts, by means wheels 83 and 88.

the pins 80 81 acts on the wheel 82, so as to` cause the series ofwheels 82 83 84 to constantly turn in the direction of the arrow, Fig.6. Catching in the ratchet-wheel 84, as also in the ratchet-wheel 89,are spring-pawls 96, Figs. 4 and 5, attached to the walls of the box forthe purpose of preventin the series of wheels from turning backwar Thearmature 7 2 between the poles of the electromagnets 65 66 is disposedin the samewway as the armature 73 and durin its oscillations of pins 8081, ig. 4, similar to those above described, on the intermediate wheel87 of the series of wheels 87 88 89.

This series of wheels is turned during the os-v cillations'of thearmature 72 in the opposite direction to that in which the series ofwheels 82 83 84 is moved by the pins 80 81, acting.

on the wheel 82, as clearly indicated by the arrow, Fig. 6. Thewheels 9495 are thus caused to roll and rotate the spur-wheel 92 in LAone' or theother direction, according asAthe one or the other of the electromagnetpairs 65 66 and 67 68 is energized by the current and the correspondingarmature 72 or 73 is put in oscillation. The spur-wheel 92 meshes with aspur-wheel 97, attached to a shaft 98 parallel with the shaft 85. (Seealso Figs. 4 and 5l) Shaft 98 is provided with a worm 99, e'ngaging aworm-Wheel 100, attached to'a verticalrshat 101, at the upper end ofwhich there is aworm 102, engaging a worm-wheel 103, fastened to one endof a screw-spindle .104, journaled in the pointer 55. In order tocompensate for errors of measurement due to `the curvature of thesur/face of the earth, the threads of the screw-s indle can suitablyincrease in pitch .toward t e outer end. The screw-spindle 104 isengaged by a nut, forming a part lof the cursor 57, which is thusbrought to move along the pointer 55 in one or the other direction,according as the one or the other of the electromagnet pairs 65 66 and67 68 isenergized by the current, this in its turn being dependent uponthe direction in which the inductor 35 is turned by means of the crank14. (Compare the diagram Fig. 7.) It is easily understood that thecursor 57 can be made to move along the pointer 55 proportionally withthe movement of the cursor` 9 of the determinator. f

The arrangements for the'transmission of i motion from the armatures 7071,l operated by each of the electromagnet pairs 61 62 and 6364, Vto thepointer 55 are perfectly analogous wi h those bywhich the cursor 57 islbrought to move along the pointer. According as one or the other of theelectromagnet airs 61 62 and 63 64 is ener ized by the current and putsthe correspon ing armature with the pointer wa/Ds. l l the form ofconstruction of the deteror 71, respectively, 105, corresponding toshaft 98, is-caused to rotate in one or the other direction. The shaft105 is provided with a worm 106, engaging a Worm-wheel segment 107connected 55, the center of said segment coinciding with the fulcrum ofsaid pointer. The pointer is thus brou ht to turn in one or the otherdirection accor ing as one or the other of the electromagnet pair 61 62or 63 64 is ener ized by the current. This in its turn bein which the inluctor 36 is Cturned by means of the crank 23, itis easy to understandthat the pointer 55 can be made to repeat exactly the same motion as thehorizontal move-v ment of the telescope of the determinator.

The cursor 57 is iitted with a pin 108 catching in a groove or slot 109in the index 59. In consequence of the combined movements of the pointer55andthe cursor 57 the index 59 will always bear in a direction exactlycorresponding to that of the observed object with relation to the placeof ring..

This direction may be read oil' directly from either of the twograduated scales 110 111,

for which purpose two apertures 112 113 are madein the index 59, eachprovided with two sighting-threads, one of which is placed verticallyabove the other. The reason why the map 53 is provided with twograduated scales 1 10 1.11 is to make it possible to always read oiifthe direction of the index 59, even when the pointer 55 partly orentirely hides or covers the one or the other of the apertures 112 and113 in the index 59. The object in view may, however, be attained withonly one graduated scale, if this one be given a ,sufficiently largeradius. The distance from the iiring place to the object watched fromthe place of observation is indicated by the scale 58 at the point wherethe scale is intersected by the sighting-threads of the pointer 55 andthose of the cursor 57. Thus the exact range and bearing of the objectwatched from the place of observation may at any moment be ascertainedat the place of 'Firing without any reading being necessary at theformer place. All the movements of the object under observation may benarrowly in oscillation the shaft ependent of the direction ICO IIC

watched from the firing place in spite of the l fact that the object isnot visible from there.

The describedarrangements for! causing the pointer 55 to turn around apoint on the map corresponding to the place A,of observation and formoving the cursor 57 along the pointer only serve to explain theprinciple of the invention and may be substituted b any other suitablearrangements by whic lthe' same result can be attained'. The circuits bywhich the electrical impulses are transmittedy from the determinator tothe electromagnets of the indicator may be arranged indifferent 55 1'26is electrically connected with one `of two Amayv f course be usedforother purposes minator shown in Fig. 8 the movement of the and brush 139conductors144 145 146, cor- 65 telescope about its fulcrum or pins 5 isefresponding, respectively, to conductors 44, fected by means of amovable screw 115 45, and 46, ig. 7, lead to the contacts 47 48 againstthe ruler 10,- the upper part of the '49'shown in Fig. 7 Thecurrent-transform- 5 screw, which is of angular section, bein fit,` ingarrangements and contacts at the crankted in a correspondingv apertureina gui ingshaft, by means of which the telescope is 7o sleeve 116,while its lower screw-threaded turned in the horizontal lane, may beanalpart is screwed into a boring in the upper ogous. The action on t 1eindicator of the part of a vertical shaft 117. When the'shaftdeterminator shown in Figs. 8 and 9 is the io 1'17 is turned in eitherdirection, the screw same as that before described.

115, which cannot turn on account of the 1 When using the apparatus, theindicator 75 guiding-sleeve 116, is given a corresponding should firstbe adjusted, which can be done motion upward or downward. The shaft bydirecting the telescope of the determina- 117 is turned by means of thecrank 14, Fig. tor toward a certain mark in the iield of view r 5 9, theshaft of which is provided with a worm (the zero-mark) at the same timeas Hthe f 118, engaging aWorm-wheel119, attached to pointer and thecursor of the indicator are 8o the lower end of the shaft 117 Inasmuchas moved by hand to the zero-point set off in the motion of screw 115may be very small, the indicator-map. The sighting-line of the thegearing from the crank-shaft should be pointer determined by the twosighting- 2o rather large. j threads then points in the same directionon The form of construction of the determinathe map as the optical axisof the telescope in 85 tor shown in Figs. 8 to 10 is in distinctionrelation to the yfield of observation, so that a from that shown in Fig.1, intended to work plane through thek sighting-threads of the withbattery-current instead of with alterpointer will intersect the sameoints on the nating currents. Disposed on a wall 120 in mapas a verticalplane throug the optical the operation-box 3 concentrically with theaxis of the telescope inthe field. The posi- 9o crank-shaft and at aninterdistance of ninety tion of the cursor corres onds, too, with thedegrees are four isolated contacts 121 122 123 angle of depression ofthe telescope. After 124. In Fig. 9 only two of these contacts are theseadjustments having/been made and the 3o visible. Every other of thesecontacts is connections having been put in order the inconnected withthe positive and every other struments are ready for use by turning the95 with the negative pole of an electric battery cranks of thedeterminator until the hair diaor other current source. `(Not shown.)Fasphragm of the telescope falls in withthe obtened to the crank-shaftis al disk 126, carryserved objectfor instance, the Water-line of V ingtwo isolated contacts 127 128, placed at a ship. In operation thepointer of the indithe same distance from the crank-shaft as cator isturned an angleof exactly the same loo the contacts 121 122 123 124 onthe wall 120 size as thatdescribed by the optical axis of and at adistance from each other of ninety dethe telescope, and at the same timethe cursor grecs. On turning the crank-shaft the conmoves along thepointer to the spot on thev 4o tacts 127 and 128 are alternately broughtin map corresponding to the position of the obcontactwith a positive andanegative contact ject under observation. Thus the position 1o; on wall120.f lThe contacts 127 and 128 may of the object is indicated on themap by a conveniently have an oblong form, vso that vertical linethrough the sighting-threads of the same after leaving a positivecontact on the pointer and of the cursor. Proceeding as wall 120immediately touch a negative constated, it is thus possiblerthroughobservatact, and inversely. Thus when the crank tion from a single pointto indicate auto- 11o 14 is turned the polarity of the contacts 127matically the position of an object at any and 128 on the disk 126changesv continumoment and at any spot, however distant ously. Thecontacts for the conductingfrom the place of observation.

wires leading to the indicator may be arl The advantages gained by thesystem deranged in the same manner as the contacts scribed as comparedwith the methods hith- I 5 at the inductor-shafts of the determinatorerto employed in secondary bombardment described with reference to Figs.11 and 2. are so eat and palpable that comments Each of the contacts 127and 128 on the disk would e superfiuous. YThe instruments rings 137 and138, fastened to the crankthan secondary bombardmentfor instance, 12oshaft. Placed around the ring 138 is a sleeve in firing mines, &c., orfor taking ranges at 140, provided with a contact-finger 143, ensie esor the like. i

tering between two fixed contacts 141 142. ith slight modifications indetailsthe ap- When the crank-shaft is turned in/ieither diparatusdescribed can be easily adjusted so rctiomthe contact-finger 143 isbrought in as to automaticall compensate for different 125 contact withone or the other of the contacts water-levels. (hig -water andloW-water,)

141 and 142.l A brush 139 presses against for the error of temperature,the wind, the the ring 137, andfrom the contacts 141 142 rotation of theprojectile, &c.

Having now described my invention, what I claim as new, and desire tosecure by Let- 1. In an apparatus for automatically indicating, at areceiving-station, the instantaneous position of an object observed froma sin le observing-station, the combination wit a sighting apparatus atthe observing.- station, a map or chartat the receiving-station, apointer adapted to move over the said map or chart, and means for movingthe said pointer in accordance with the horizon.-

tal movement of the sighting apparatus, of' -a cursor adapted to movealong the said pointer, means for causing the cursor to automaticallymove inwardly or outwardly according as the sighting apparatus isadjusted for a more or less distant object, and

' a second pointer or index moved by the said a cursor adapted to movealong the said pointerf means for causing the cursor to automaticallymove inwardly or outwardly according as the angle of depression of thesihting apparatus is increased or decrease and a second pointer or'index moved by the said cursor about a point of the map cr chartcorresponding to the receiving-station, substantially as described.

3. Apparatus forautomatically indicating, at a receiving-station, ,theinstantaneous position of an object observed from ai singleobserving-station characterized bythe cogmbination of a sig tingapparatus I the observing-station, a crank by which 'the angle ofdepression of the sighting apparatus can be altered as desired, meansoperated by the crank 'for transmitting an alternating current from theobserving-station, two contact-pieces at the said station, a contactiner adapted to be brou ht into contact wit one or the other of t e saidcontactpieces, according as the crank is rotated in one or the otherdirection, circuits connected with the said contact-pieces,electromagnets included in each of the said circuits, polarizedarmatures o erated by the said 'electromagnets, a movable pointer, meansfor moving the said ointer in synchronism with the movement o thesighting apparatus the horizontal plane, a screw rotatablymounted in thesaid pointer, means for transmitting motion from the armatures of theelectroplaced at magnets to the said screw, so as to cause the y latterto rotate in one' or the other direction, according to the directionofvrotation ofthe crank -at the observing-station, and a cursor mountedon the said sciew'in suchsa manner as to be moved in one or the otherdirection along the screw according to the direction of KARL OSKAR LEON.

Witnesses: i

SVEN' OTTO SviiNssoN,` Emo J oHANssoN. f

nrotation of the latter, substantially as de- I

